Japanese Patent Application Publication No. 2008-292523 describes a fusion splicer that includes a grasping structure that grasps a loose buffer optical fiber formed by loosely inserting an optical-fiber strand into a tube. The grasping structure grasps a loose buffer optical fiber by elastically pressing a tube portion of the loose buffer optical fiber placed on a holder base against the holder base.
However, when the tube of the loose buffer optical fiber has a predetermined hardness or higher, the existing grasping structure fails to grasp and fix in place the optical-fiber strand inserted into the tube even by elastically pressing the tube portion against the holder base. In view of this situation, in order to grasp and fix in place an optical-fiber strand, the optical-fiber strand, not the tube portion, has to be directly grasped.
Generally, the ratio of the length of a bare fiber protruding from the optical-fiber strand to the length of an optical-fiber strand protruding from a tube or a coating of an optical fiber buffer differs between a loose buffer optical fiber and a tight buffer optical fiber. More specifically, the ratio of the exposed bare fiber to the exposed optical fiber strand is larger in a tight buffer optical fiber than in a loose buffer optical fiber. Therefore, if an existing grasping structure configured such that the optical-fiber strand of a loose buffer optical fiber is directly grasped is used for a tight buffer optical fiber, the grasping structure would grasp the bare fiber, thereby making it more likely to damage the bare fiber.